Aminophenylamidines as anthelmintic agents

ABSTRACT

4-Amino substituted phenylamidines as anthelmintics. The compounds, of which N-(4-aminophenyl)-N&#39;&#39;, -N&#39;&#39;-dimethylacetamidine is a representative embodiment, can be prepared through treatment of a 4-amino aniline with a carboxylic acidamide or thioamide, reduction of an appropriately substituted 4-amino-phenylamidine, optionally followed by alkylation of the resultant 4aminophenylamidine, formation of a Schiff base followed by quaternization and hydrolysis, or hydrolysis of a 4acylaminophenylamidine.

United States Patent [191 Wollweber et al.

[ 51 Sept. 2, 1975 AMINOPHENYLAMIDINES AS ANTHELMINTIC AGENTS [75] Inventors: Hartmund Wollweber,

Wuppertal-Elberfeld, Germany; Winfried Flucke, Beenleigh, Australia [73] Assignee: Bayer Aktiengesellschaft, Germany [22] Filed: Jan. 30, 1973 [21] Appl. No.: 328,146

Related US. Application Data [62] Division of Ser. No. 151,575, June 9, 1971, Pat. No.

[30] Foreign Application Priority Data June 13, 1970 Germany 2029299 [52] US. Cl. 424/326; 424/244; 424/263;

424/267; 424/274; 424/304 [51] Int. Cl. A61K 27/00 [58] Field of Search 151/575; 424/326 [56] References Cited UNITED STATES PATENTS 3,182,053 5/1965 Steiger 260/156 3,189,648 6/1965 Gerjovich 260/561 3,462,537 8/1969 Reinach 424/326 3,729,565 4/1973 Harrison et a1. 424/326 OTHER PUBLICATIONS J. Org. Chem. Vol. 29, (1964) pp. 3697-3700.

Primary Examiner-Frederick E. Waddell 57 ABSTRACT I Schiff base followed by quaternization and hydrolysis,

or hydrolysis of a 4-acylaminophenylamidine.

61 Claims, No Drawings AMINOPHENYLAMIDINES. AS ANTHELMINTIC AGENTS a This is a division of application Ser. No. 151,575 filed June 9, 1971, now US. Pat. No. 3,855,292.

The present invention relates to new aminophenylamidines and -cycloamidines and salts thereof, to processes for their production, and to their use as medicines, especially as parasiticides.

Acylaminophenylformamidines, such as N-(pacetamidophenyl )-N ,N '-dimethylformamidine (US. Pat. No. 3,184,482) are already known. This compound, as well as other formamidine derivatives, are, however, ineffective against helminths. Furthermore, N-phenylacetamidines, such as N-(p-chlorophenyl)- N,N-dimethylacetamidine, are known. These compounds are also ineffective against helminths.

This invention provides aminophenylamidines and aminophenylcycloamidines of the general formula:

in which:

R is a hydrogen atom or a straightor branchedchain alkyl, alkoxy alkyl or alkenyl group;

R and R are the same or different and are each a hydrogen, fluorine, chlorine or bromine atom or a straightor branched-chain alkyl, alkenyl, or alkoxy group or a cyano or trifluoromethyl group;

R is a straightor branched-chain alkyl or alkenyl group or a cycloalkyl group; and

either R is a straightor branched-chain alkyl, alkenyl or alkoxy group; and

R is a hydrogen atom or a straightor branchedchain alkyl, alkenyl, alkynyl or alkoxy group;

R and R together with the amino nitrogen atom and the amidino carbon atom form a five, six or sevenmembered ring;

and their salts.

These aminophenylamidines and -cycloamidines and their non-toxic salts are useful for combating parasites, especially helminths, in human and veterinary medicine.

Alkyl and alkoxy groups R preferably contain one to five, especially one or two, carbon atoms, and the alkenyl group R preferably contains two to five carbon atoms.

Alkyl groups R preferably contain one to five, most preferably one or two, carbon atoms, and alkenyl groups R generally contain two to five, preferably two or three, carbon atoms.

Alkyl and alkoxy groups R and R preferably contain one to six, especially one to three, carbon atoms, and alkenyl groups R and R preferably contain two to six, especially two to four, carbon atoms.

Alkyl and alkoxy groups R? preferably contain one to four, especially one to three, carbon atoms. The alk e nyl and alkynyl groups R l preferably contain two .to four carbon atoms. I

If R and R together with the amine nitrogen atom form a S-membered to 7-membered ring, R and R together preferably represent the group (CH in which n represents 3, 4 or 5.

The alkyl groups R preferably contain one to five, especially one to three, carbon atoms, and the alkenyl groups R preferably contain two to five, especially two or three, carbon atoms. The cycloalkyl group R preferably possesses three to seven carbon atoms.

The active substances according to the invention are basic in character. They can be used as free bases or in the form of their salts, for example hydrohalides, such as, for example, hydrochlorides, sulphates, phosphates, nitrates, acetates, naphthalene disulphonates or pamoates, i.e., the salts with methylene-bis-(2- hydroxynaphthoic acid-3). The preferred salts are the hydrochlorides.

Particularly preferred compounds are those of the general formula (1) in which:

R is a hydrogen atom or an alkyl or alkenyl group containing up to three carbon atoms; R is a hydrogen, chlorine or bromine atom or a methyl or cyano group; I

R is a hydrogen, chlorine or bromine atom or an alkyl group with up to three carbon atoms or a methoxy, trifluoromethyl or cyano group;

R is methyl or ethyl group; and either R is a methyl or ethyl group or a cycloalkyl group with three to six carbon atoms; and

R is an alkyl or alkoxy group with one to three carbon atoms;

R and R together are a-(CHfi group, m being a whole number from 3 to 5;

and their salts.

The invention further provides four processes designated as (a), (b), (c) and (d) for the production of the new aminophenylamidines and -cycloamidines and their salts.

Process (a) comprises reacting an aniline derivative of the general formula with a carboxylic acid amide or thioamide of the general formula:

or with a salt or a reactive derivative thereof. In general formulae (2) and (3) W is an oxygen or sulphur atom and R, R and R to R are as defined above.

The reaction is optionally carried out in the presence of a condensation agent. The reaction product can be isolated in the form of one of its salts or in the form of a free base, and then optionally converted into any other desired salt. g

As salts of the carboxylic acid amides (3) there'are to be understood both salts with organic acids, (for example, the acetates) and salts with inorganic acids (for example the hydrohalides or sulphates).

. By .reactive derivatives of the amides (3) thereare, for example, to be understood derivatives which are obtained by reaction of an amide orfthioamide of the general formula (3) with an inorganicacid (for example, hydrochloric acid, boron trichloride or sulphuric acid) or with an inorganic or organic acid halide (for example, phosphorus oxychloride, phosphorus pentachloride, phosgene, thionyl chloride, benzoyl bromide, p-toluenesulphonyl chloride or a mixture of phosgene/aluminium chloride, or phosgene/hydrogen chloride or phosgene, phosphorus oxychloride) or with a trialkyloxonium fluorborate (1 carbon atoms per alkyl group) or with a dialkyl sulphate (l 5 carbon atoms per alkyl group) or an alkyl halide l 5 carbon atoms).

As condensation agents that can be employed in process (a), there may for example be mentioned:

Inorganic acids (for example, hydrochloric acid, boron trichloride, sulphuric acid) or inorganic or organic acid halides (for example phosphorus oxychloride, phosphorus pentachloride, phosgene, thionyl chloride, benzoyl bromide, p-toluenesulphonyl chloride or a mixture of phosgene/aluminium chloride, or phosgene/hydrogen chloride or phosgene/phosphorus oxychloride) or trialkyloxonium fluorborates (one to five carbon atoms per alkyl group) or dialkyl sulphates (one to five carbon atoms per alkyl group) or alkyl halides (one to five carbon atoms).

When a thioamide is used, i.e., W sulphur in general formula (3), a desulphurizing agent, for example, HgO, Ag O or Hg(CN) can be used advantageously in addition to one of the abovementioned condensation agents, or without one of these condensation agents.

The reaction components (2) and (3) are preferably employed in the stoichiometrically required amounts.

The reaction can be carried out in any inert organic solvent; among such solvents, aromatic, optionally halogenated, hydrocarbons, for example, benzene, toluene or dichlorobenzene; optionally chlorinated aliphatic hydrocarbons, for example methylene chloride and chloroform; tetramethylene-sulphone, and lower aliphatic alcohols, for example, methanol and ethanol, should be mentioned.

The reactants are preferably brought together at room temperature (about C) and, if appropriate, are warmed to between 30 and 150C, preferably 80 to 120C, in order to complete the reaction.

The success of the reaction does not depend on the sequence in which the reactants are brought together. The new compounds are isolated in the customary manner.

Process (12) comprises reducing nitrophenylamidine or -cycloamidine of the general formula:

or a salt thereof,- to obtain" an aminophenylamidine or -cycloamidine, of the general formula:

i.e., a compound of general formula l inwhich R is hydrogen. This product is then, if -a compound of general formula (1) is required in which R is not hydrogen, either i. alkylated with an alkylating agent of the general formula ii. alkylated reductively with an oxo compound of the general formula:

to obtain a Schiff base which is reduced to give the required aminophenylamidine, -cycloamidine or salt.

In the above general formulae (4), (6) and (7), R, R, R to R are as defined above, B is a reactive ester group or a halogen atom; R is a straight-chain or branched alkyl or alkenyl group; R is a hydrogen atoin or an alkyl group: and R is an alkyl group.

Straight-chain or branched alkyl groups R preferably contain one to five carbon atoms, especially one or two carbon atoms.

Halogen atoms B are preferably chlorine or bromine atoms. Reactive ester groups B are, for example, my]- sulphonyloxy, for example, benzenesulphonyloxy or tosyloxy, or alkylsulphonyloxy, for example methanesulphonyloxy, or alkoxysulphonyloxy (preferably with one or two carbon atoms in the alkyl or alkoxy group).

The alkyl groups R preferably contain one to five,

especially one to four, carbon atoms and the alkyl groups R preferably contain one to five, especially one or two, carbon atoms.

The nitrophenylamidines of general formula (4) and their salts can be reduced by any suitable method.

The reduction can advantageously be effected catalytically, for example'with Raney nickel as the catalyst,

The reduction can also be carried out with zinc/hydrochloric acid and stannous chloride, preferably in an aqueous medium (water).

Furthermore, the reduction can be carried out with sodium sulphide, for example insan alcohol, for example, methanol and ethanol, or in an ether, for example, in tetrahydrofuran, at temperatures of 20 to 100C, preferably at the boiling point of the solvent.

Further reducing agents which can be used are complex metal hydrides, such as, for example, sodium boranate in alcohol (preferably ethanol)/water, at tempera tures of, preferably, 20 to 80C.

In process b (i) l to 2 mols of the alkylating agent of general formula (6) are preferably employed per mol of the intermediate compound (5).

Examples of suitable solvents for use in step (i) are water, alcohols, for example, methanol or ethanol, ketones, for example, acetone, ethers, for example, tetrahydrofuran, aromatic hydrocarbons, for example, benzene or toluene, or mixtures of these solvents. An increase in the yields can be achieved by the addition of auxiliary bases such as, for example, sodium hydroxide, sodium and potassium carbonate, pyridine or triethylamine.

The reaction is carried out at 0 100C, preferably at 10 to 40C.

In process b (ii) the reactants (5) and (7) are preferably employed in approximately molar amounts. Solvents which can be used for this reaction, which is carried out at 0 to 100C, preferably at about 20 to 60C, are, for example, alcohols, for example, methanol or ethanol, ethers, for example, tetrahydrofuran, and aromatic hydrocarbons, for example, benzene or toluene. The Schiffs base obtained in this manner is hydrogenated, optionally being isolated, by any suitable method. For instance, the base may be catalytically hydrogenated, for example with Raney nickel as the catalyst. The catalytic reduction is preferably carried out at room temperature (about 20C), and optionally under pressure l to 80 atmospheres gauge, preferably 60 at mospheres gauge). As a solvent an alcohol, for example methanol and ethanol, an aromatic hydrocarbon, for

example, benzene and toluene, or an ether, for example, tetrahydrofuran, can be used.

The reduction of the Schiffs base can also be effected by means of a complex metal hydride (approximately stoichiometrically required amounts), for exam ple, sodium borohydride. In this case the reaction is carried out at temperatures of 20 to 80C. Here, alcohols, for example methanol and ethanol, optionally in admixture with water, are preferably used as solvents.

Process (0) comprises reacting an aminophenylamidine or -cycloamidine of the general formula:

and subsequently hydrolytically splitting off the aldehyde portion of the product. If a salt is required this is then produced in any suitable manner.

In general formulae (5) and (6), R, R to R and B are as defined above.

In process (0), the compound of the general formula (5) is reacted with any suitable aldehyde, for example, acetaldehyde or benzaldehyde, according to any suitable method, to give the Schiff base. The reactants are preferably employed in molar amounts. The reaction temperatures are preferably between 0 and C, preferably between 20 and 40C. Any inert organic solvent may be used, for instance, an alcohol, for example methanol and ethanol, an aromatic hydrocarbon, for example benzene and toluene, or an ether, for example tetrahydrofuran.

The Schiff base is quaternised, optionally after being isolated, by means of the alkylating agent (6) by any suitable method, preferably at temperatures between 20 to 100C, especially between 60 to 80C. Any inert organic solvent, for example benzene, toluene and tetrahydrofuran can be employed. The subsequent hydrolysis is preferably carried out without isolation of the quaternised Schiff base, preferably at temperatures between 20 to 100C, especially between 40 and C, and preferably in an aqueous alcohol, especially ethano].

Process (d) comprises hydrolytic splitting of an acylaminophenylamidine or -cycloamidine of the general formula:

in which R, R and R to R are as defined above and R is an acyl or acyloxy group, preferably with l 5 carbon atoms.

The hydrolytic splitting is carried out by any suitable method; many such methods are, known in the art.

The hydrolysis ispreferably carried out in the presence of a strong acid, such as hydrochloric acid or sulphuric acid. Water, or a mixture of water with an alcohol, is used as a solvent. The hydrolysis is preferably carried out atthe boiling point of the solvent.

The following. Examples illustrate the process according to the invention for the production of the new aminophenylamidines and cycloamidines.

All temperatures are given in degrees centigrade (C).

All starting compounds are known or are obtainable by known processes.

EXAMPLE 1 CIH, /CH, H,N- N=CN 9 620 g (3 mols) of N-(4-nitropheny1)-N,N'- dimethylacetamidine in 1250 ml of ethanolic hydrochloric acid (3.3 mols) are hydrogenated with the aid of Raney nickel as the catalyst, at 70 80 and 80 to 100 atmospheres gauge hydrogen pressure. The mixture is evaporated in vacuo, the residue is taken up in water and rendered alkaline with sodium hydroxide solution, the base which separates out is extracted with ether, the extract is evaporated, and the residueis distilled in vacuo; the product is N-(4-aminopheny1)- -N,N-dimethylacetamidine, boiling point 158 165, melting point 93 95 (from ethyl acetate); yield 426.5 g, monohydrochloride, melting point 273 The following compounds are obtained by analogous processes:

III R RI'II RV 1-1,N N C N Rl'l H,N R R" R" R" R"' Boiling point/ mm Hg 4-NH2 H 2-Cl CH, CH, CH, l72/0.3 4-NH2 H 3-Cl CH, CH, CH, 170/0.3 4-NH2 2-Cl 6-C1 CH, CH, CH, l90/0.5 4-NH2 H 2-CH;, CH, CH, CH, l75/0.6 4-NH H 2- CH, CH, CH, 1 80/O.4

OCH, 4-NH2 H 2-CF, CH, CH, CH, l73/().3 4/NH H 2-CN CH, CH, CH, 168/O.2 4-NH, 2-CN 6-CN CH, CH, CH, 1s4/0.3 4-NH2 H 2-Br CH, CH, CH, l85/O.4 4-NH H 2-C,H CH, CH, CH, |83/0.4 4-NH, H H CH, CH, C,H, l66/0.3 4-NH2 H H CH, CH, C;,H-, l74/O.3 4-NH, H H CH, C,H CH, 171/0.3 4NH, H H CH, C,H-, CH, 178/0.3 4-NH H H C,H C,H, CH, 180/0.3 4-NH, H H H CH, CH, 154/0.2 d-NH, H H H C,H, CH, 160/0.2 4-NH, H H H C,H CH, l68/0.2 4-NH H H H H CH3 4-NH H H CH, OCH, CH, l63/().2 2 H H CH, OC,H, CH, 168/().2 4-NH 2-C1 H CH, OCH, CH, 175/0.2

EXAMPLE 2 The following compounds are produced in accordance with the method described in Example 1, by reduction of 2-(nitro-phenylimino)-azacyc1oalkanes:

n H N R'" R R" Boiling point/ mm Hg 3 4-NH H H CH, 170/0,1 Melting point -86 3 4-NH 2-C1 H CH, Melting point 9192 3 4-NH, 2-CH, H CH, 190/(). 1 3 4-NH 2-Br H CH, 205/0.l 3 4-NH 3-C1 H CH, |93/0.2 3 4--NH 3-CH H CH, 192/0. 1 3 4-NH 2-C1 6-Cl CH, 2 10/O.2 3 4-NH 2-CN H CH, 181/0.2 3 4-NH H H C,H 174/0.2 3 4--NH 2-Cl H H, 188/0.1 4 4-NH H H CH, l78/0. 1 4 4-NH 2-Cl H CH, 196/0.1 5 4-NH 2-Cl H CH, 203/0.| 5 4-NH H H CH, |93/0. 1 3 4-NH H H H 178/O.2 3 4-NH Z-CF, H CH, Melting point 182/0.2

EXAMPLE 3 TH, /CH, CH,HN N=CN (12) 23 g of isobutyraldehyde are added dropwise, at 20, to 53 g (0.3 mol) of N-(4-aminophenyl)-N,N'- dimethylacetamidine, dissolved in 500 ml of benzene, the mixture is heated for 7 hours whilst connected to a water separator, and the isobutylideneaminophenyl)-N',N- dimethylacetamidine is distilled in vacuo; boiling point 156 160. 8.3 g (0.066 mol) of dimethyl sulphate are added to 13 g (0.056 mol) of this compound, dissolved in ml of benzene, the mixture is heated for one hour under reflux, the benzene is decanted off, the residue is taken up in 50 ml of 50% strength ethanol, and the mixture is heated for one hour under reflux. After evaporation in vacuo, and treatment of the residue with sodium hydroxide solution, the free base is extracted with ether and distilled: boiling point hydrochloride, melting point 226 228.

The following compounds are produced by analogous processes:

35 g of the N-(4-isobutylideneaminophenyl)-N',N'- dimethylacetamidine obtained according to Example 3, dissolved in 250 ml of tetrahydrofuran, are hydrogenated with Raney nickelas the catalyst, at 20 50 and 60 atmospheres gauge of hydrogen. After filtering off the catalyst, and distilling, 17.5 g of N-(4- isobutylaminophenyl )-N ',N '-dimethylacetamidine, boiling point l38l45, are obtained.

Successive reaction of 2-(4-aminophenyl)-irnino;N- methylpyrrolidine with benzaldehyde and dimethyl sulphate, in accordance with the method described in Example 3, yields 2-(4-methylaminophenyl)-imino-N- methylpyrroline, boiling point 01 175.

The following compounds are produced in a corresponding way:

25 g of N-(4-carbethoxyaminophenyl)-N',N'- dimethylacetamicline in ml of concentrated hydrochloric acid are heated for 2 hours under reflux. After evaporation, the residue is taken up in water and rendered alkaline with sodium hydroxide solution, and the aqueous phase is extracted with a mixture of ether and chloroform. After distillation, 12 g of N-(4- aminophenyl)-N',N'-dimethylacetamidine, boiling point M l58-l65, melting point 9395, are obtained.

The fact that the new aminophenylamidines and cycloamidines and their salts show a strong and wideranging anthelmintic activity is surprising and unforeseeable.

The new compounds are substantially more effective than other known anthelmintics of the same general action, such as, for example, bephenium hydroxynaphthoates, 1,4 phenylenediisothiocyanate, perchloroethylene, thiabendazole and parbendazole.

Special attention is drawn to the fact that excellent results are achieved with a single administration of the new compounds.

The provision by the invention of these new compounds constitutes a substantial extension of the available rarige of anthelmintics.

In particular, the compounds manufactured according to the invention for example display a surprisingly good and broad action against the following helminths (nematodes and cestodes):

I. Nematodes l. Ancylostoma caninum, Uncinaria stenocephala and Bunostomum trigonocephalum (hookworms) from the family of the Ancylostomatidae;

2. Haemonchus contortus, Trichostrongylus colubriformis, Cooperia punctata, Ostertagia circumcincta, Nippostrongylus muris and Nematospiraides dubius (worms of the stomach and small intestine) from the family of the Trichostrongylidae;

3. ()esophagostumum columbianum and Chabertia ovina (worms of the large intestine) from the family of the Strongylidac;

4. Strongyloides ratti (dwarf threadworms) from the family of the Rhabditidae;

5. Toxocara canis, Tuxascaris leonina and Ascaris suum larvae (coilworms) from the family of the v Ascarididae;

6. 'Aspiculuris tetraplera (maggot worms) from the family of the Oxyuridae;

EXAMPLE A Hookworm Test/Dogs Dogs experimentally infected with Ancylostoma ca ninumwere treated after the end of the pre-patent period of the parasites.

The amount of active compound was administered orally, as the pure active compound or dissolved in strength lactic acid, in gelatine capsules.

The degree of action was determined by counting the worms expelled after treatment and the worms remaining in the text animal after dissection, and calculating the percentage of worms expelled.-

The active compounds tested, the dosages used, and the action are summarised in the table which follows.

Table l Hookworm Test/Dogs Active compounds Dose Action mg/kg in '7 known compound for comparison:

/CH:| CH;,-CONH N=CHN .HCl I7) 50 0 3 Cl Na f-N l 8) 0 Q \CH Cl-C C-Cl I9) 300 82 Cl C] S=C=N N=C=S (20) 5 l O-(CH: N(CH;,). -CH 6O 46 (23) I00 0 N N S CH CH l H,N N=C N 9 5 99 3 2.5 99 69 CH CH H N N=CN .HCl (24) I0 94 H N N- 10 92 5 27 Cl CH H N Ni 1 Table 1 Continued Hook-worm Test/ Dogs CH3 C l Dose Action mg/kg in 7r Literature: Rawcs, D.A. IQf-l )2 The activity of Bcphenium Hydrocynaphthoatc against Hookworms in the Dog Vet.Rcc. 73 [6). 390-392 Literature. Theotlorides, VJv and M. Ladermun (I968):

Parhendzlzolc in the Treatment of Intestinal Nematodes of Dogs and Monkeys. VcLMI-d. 63 l), 9X5.

EXAMPLE BHookworm Test/Sheep Sheep experimentally infected with Bunostomum trigonocephalum were treated after the end of the prepatent period of the parasites.

The amount of active compound was administered maining in the test animals, after dissection, and calculating the percentage of worms expelled.

The active compounds tested, the dosages used and the action are shown in the table which follows. Table 3: Test on Worm of Large/Sheep orally, as pure active compound, in gelatine capsules. Active Compound Dose Action The degree of action was determined by counting the in worms expelled after the treatment and the worms re- CH CH maining in the test animals, after dissection, and calculating the percentage of worms expelled. -N=C-N 10 97 The active compounds tested, the dosages used and CH. the action are shown in the table which follows. J

Table 2: Bookworm Test/Sheep Active compounds Dose i Action mg /kg in 7:

('1ll 3 Base 4 5 1 95 2 (9) Base 10 L00 Hydrochloride 5 100 5 3 CH 1 a N N=C-N (29) 10 97 CH Cl H N- N=[ (2 23 83 I l '3 l EXAMPLE CTest on Worm of Large Intestine/Sheep EXAMPLE DCoilworm Test/Dog Dogs naturally infected with Toxocara canis or Toxascaris leonina were treated orally. The amount of active compound was administered orally, as pure active compound or as a 10% strength solution in lactic acid, in gelatine capsules.

The degree of action is determined by counting the worms expelled after the treatment and the worms remaining in the test animals, after dissection, and calculating the percentage of worms expelled.

The active compounds tested, dosages used and action are summarised in the table which follows. Table 4: Coilworm Test/Dog In general it has proved advantageous to administer amounts of 0.1 to 50 mg of the new compounds per kg of body weight per day in order to achieve effective results.

Nevertheless it may at times be necessary to deviate from the amounts mentioned, and in particular to do so as a function of the body weight of the test animal or of the nature of the method of administration, but also because of the variety of animal and its individual behaviour towards the medicament or because of the nature of the formulation of the latter and the point in time, or interval, at which it is administered. Thus, it may in some cases suffice to use less than the abovementioned minimum amount, whilst in other cases the upper limit mentioned must be exceeded. Where major amounts are administered, it may be advisable to divide these into several individual administrations over the course of a day. The same dosage range is envisaged for administration in human medicine and in veterinary medicine. The general sense of the other comments made above also applies.

As stated above, this invention also relates to the pharmaceutical use of the new aminophenylamidines and -cycloamidines and their non-toxic salts.

Accordingly, the present invention provides a pharmaceutical composition containing as an active ingredient at least one of the new aminophenylamidines and -cycloamidines of the general formula 1) given above, or a non-toxic salt thereof, in admixture with a pharmaceutically acceptable solid or liquid diluent or carrier as hereinafter defined.

In the present specification the expression pharmaceutically acceptable diluent or carrier means a nontoxic substance that mixed with the active ingredient or ingredients renders it suitable for administration.-The expression preferably excludes water and lowmolecular weight organic solvents commonly used in chemical synthesis, except in the presence of other pharmaceutically necessary ingredients such as salts in correct quantities to render the composition isotonic, buffers, surfactants, colouring and flavouring agents, and preservatives. Examples of suitable liquid and solid diluents and carriers are the following:

Buffered aqueous solutions; isotonic saline aqueous solutions; non-toxic organic solvents; such as paraffms, (for example petroleum fractions); vegetable oils (for ents, for example, natural ground rock (for example kaolins, aluminas, talc or chalk), synthetic rock powders (for example highly disperse silica or silicates); and sugars (for example unrefined sugar, lactose and glucose). Examples of pharmaceutical compositions according to the invention are ointments, pastes, creams, sprays, lotions, aqueous suspensions, emulsions and solutions, elixirs, syrups, granules and powders, either free-flowing or compressed into tablets.

The compounds and pharmaceutically acceptable salts of the present invention may be administered perorally.

One group of preferred pharmaceutical compositions of the invention are therefore those adapted for oral administration. The diluents and carriers used are preferably therefore those that adapt the active ingredient or ingredients for oral administration. Examples of such diluents and carriers are solid vehicles, excipients and lubricants such as glucose, lactose and sucrose, corn and potato starch, sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate, powdered gum tragacanth, gelatin, alginic acid, agar, stearic acid, sodium, calcium and magnesium stearates, sodium lauryl sulphate, sodium citrate, calcium carbonate, and dicalcium phosphate. I

The pharmaceutical compositions of the invention may also contain other non-toxic adjuvants and modifiers such as dyes, surfactants, for example, emulsifiers, such as non-ionic and anionic emulsifiers (for example polyoxyethylene-fatty acid esters, polyoxyethylenefatty alcohol ethers, alkylsulphonates and arylsulphonates), and dispersing agents (for example lignin, sulphite waste lyes, methylcellulose, starcn and polyvinylpyrrolidone), perfumes, flavouring agents, preservatives and biocides.

The compounds and pharmaceutically acceptable salts of the invention may also be administered parenterally, in particular subcutaneously. A group of preferred pharmaceutical compositions of the invention are therefore those adapted for parenteral injection. The diluents andcarriers used are therefore preferably those that adapt the active ingredient for parenteral administration. Examples of such diluents and carriers are solvents and suspending diluents such as water and water-miscible organic solvents, in particular sesame oil,

groundnut oil, aqueous propylene glycol, and N,N'-

dimethyl formamide. Examples of pharmaceutical compositions of the invention are sterile isotonic saline aqueous solutions of the active ingredient, which may be buffered with a pharmaceutically acceptable buffer and are preferably pyrogen-free.

The pharmaceutical compositions of the invention generally contain 0.5 to wt. of a new aminophenylamidine or -cycloamidine of the invention or a non-toxic salt thereof. 7

The present invention also provides medicaments in dosage unit form as hereinafter defined comprising as an active ingredient at least one aminophenylamidine or -cycloamidine of general formula l given above or a non-toxic salt thereof, either alone or in admixture with a pharmaceutically acceptablc solid or liquid diluent or carrier. In this case the diluent or carrier is preferably as defined above but can also be water or another common solvcnt.

active ingredienfls); for example, one, two, three' of fouriunit doses or a half, a third or a quarter of a unit dose. A unit doself is the amount of the active ingredient(s) to be administered on one occasion and will usually be a daily dose, or for example a half, a third, or a quarter of a daily dose depending on whether the medicament is to be administered once or, for example, twice, three times, or four times a day.

The discrete portions constituting the medicament in dosage unit form can include a protective envelope. The active ingredient can be undiluted and contained in such an envelope, or can be mixed with a pharmaceutically acceptable solid or liquid diluent or carrier as defined above. Such portions can for example be in monolithic coherent form, such as tablets, lozenges, pills, suppositories, or dragees; in wrapped or concealed form, the active ingredients being within a protective envelope, such as wrapped powders, cachets, sachets, capsules, or ampoules; or in the form of a sterile solution suitable for parenteral injection, such as ampoules of buffered, isotonic, sterile, pyrogen-free aqueous solution; or in any other form known in the art.

As stated above, it is preferred to administer the new aminophenylamidines and -cycloamidines of general formula (1) or their salts perorally. Preferred medicaments in dosage unit form according to the invention are therefore those adapted for oral administration, such as tablets, pills, dragees, capsules, and cachets, as well as wrapped powders containing the active ingredient in powdered form with a powdered diluent or carrier for suspension in water before being taken.

As stated above it is also possible to administer the new aminophenylamidines and -cycloamidines pareter- 'ally. A further group of medicaments in dosage unit form according to the invention are therefore those adapted for parenteral injection, such as ampoules containing a measured quantity of a sterile isotonic saline injectable aqueous solution of the new active ingredient, which may be buffered with a pharmaceutically acceptable buffer and are preferably free of pyrogens.

The preferred unit dose for administration of the medicaments of the invention is SO 2,250 mg. of active ingredients. This will normally be administered once daily.

The invention further provides a method of combating parasitic infestation in an animal which comprises administering to the animal (preferably parenterally or perorally) an aminophenylamidine or -cycloamidine or a non-toxic salt thereof, a pharmaceutical composition or a medicament in' dosage unit form according to the invention. i

The administration is preferably carried out orally, but may also be carried out parenterally, in particular subcutaneously.

What we claim is:

l. A pharmaceutical composition useful for treating helm intic infections in humans and animals comprising an anti-helmintically effective amount of a compound of the formula:

or a pharmaceuticallly acceptable non-toxic acid addition salt thereof, wherein R is hydrogen, alkyl of one to five carbon atoms, alkoxyalkyl of two to five carbon atoms or alkenyl of two to five carbon atoms;

each of R and R, independently of the other, is hydrogen, fluoro, chloro, bromo, alkyl of one to six carbon atoms, alkenyl of two to six carbon atoms, alkoxy of one to six carbon atoms, or trifluoromethyl;

R is alkyl of one to five carbon atoms;

R is alkyl of one to four carbon atoms, alkenyl of two to four carbon atoms, alkynyl of two to four carbon atoms, or cycloalkyl of three to six carbon atoms; and

R is hydrogen, alkyl of one to five carbon atoms or alkenyl of two to five carbon atoms, in combination with a pharmaceutically acceptable non-toxic inert diluent or carrier.

2. A composition according to claim 1 wherein said carrier is a liquid or solid carrier and said composition is in oral administration form.

3. A composition accordingto claim 1 wherein said carrier is a liquid carrier and said composition is in parenteral administration form. a r

4. A composition according to claim 1 wherein said compound is N-( 4-aminophenyl )-N ,N dimethylacetamidine or a pharmaceutically acceptable non-toxic acid addition salt thereof.

5. A composition according to claim 1 wherein said compound is N-(4-methylaminophenyl)-N',N' dimethylacetamidine or apharmaceutically acceptable non-toxic acid addition salt thereof.

6. A composition according to claim 1 wherein said compound is N-(2-chloro-4-aminophenyl)-N',N'- dimethylacetamidine or a pharmaceutically acceptable non-toxic acid addition salt thereof.

7. A composition according'to claim 1, wherein R is hydrogen, alkyl of one to three carbon atoms or alkenyl of up to three carbon atoms, R is hydrogen, chlorine, bromine or methyl, R is hydrogen, chlorine bromine,

. alkyl of one to three carbon atoms, methoxy or trifluoromethyl, R is methyl or ethyl, R is alkyl of one to three carbon atoms and R is methyl or ethyl.

8. A composition according to claim 1, wherein the compound is in the form of a salt, wherein the salt is selected from the group consisting of a hydrohalide, sulfate, phosphate, nitrate, acetate, naphthalenedisulphonate and pamoate.

9. A composition according to claim 1, wherein R and R are each alkyl of one to four carbon atoms.

10. A composition according to claim 1, wherein R is hydrogen, R is hydrogen, R is 2-chloro, R is methyl, R is methyl and R is methyl.

11. A composition according to claim 1, wherein R' is hydrogen, R is hydrogen, R is 3-chloro, R is methyl, R is methyl and R is methyl.

12. A composition according to claim 1, wherein R is hydrogen, R is 2-chloro, R is 6-chloro, R is methyl, R is methyl and R is methyl.

13. A composition according to claim 1, wherein R is hydrogen, R is hydrogen, R is Z-methyl, R is methyl, R is methyl and R is methyl.

14. A composition according to claim 1, wherein R is hydrogen, R is hydrogen, R is Z-methoxy, R is methyl, R is methyl and R is methyl.

15. A composition according to claim 1, wherein R is hydrogen, R is hydrogen, R is 2-trifluoromethyl, R is methylm R is methyl and R is methyl.

16. A composition according to claim 1, wherein R hydrogen, R is hydrogen, R is 2-bromo, R is methyl, R is methyl and R is methyl.

17. A composition according to claim 1, wherein R is hydrogen, R is hydrogen, R is 2-propyl, R is methyl, R is methyl and R is methyl.

18. A composition according to claim 1, wherein R is hydrogen, R and R are each hydrogen, R is ethyl, R and R are each methyl.

19. A composition according to claim 1, wherein R is hydrogen, R and R are each hydrogen, R is propyl, R and R are each methyl.

20. A composition according to claim 1, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is methyl and R is ethyl.

21. A composition according to claim 1, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is methyl and R is propyl.

22. A composition according to claim 1, wherein R is hydrogen, R-and R are each hydrogen, R is methyl, R and R are each ethyl.

23. A composition according to claim 1, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is hydrogen and R is methyl.

24. A composition according to claim 1, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is hydrogen and R is ethyl.

25. A composition according to claim 1, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is hydrogen and R is propyl.

26. A composition according to claim 1, wherein the compound is N-( 4-isobutylideneaminophenyl )-N ,N dimethylacetamidine.

27. composition according to claim 1, wherein R is methyl, 'R" is 2-chloro, R is hydrogen, R, R and R are methyl.

28. A composition according to claim 1, wherein R is methyl, R is 2-bromo, R is hydrogen, R, R and R are methyl.

29. A composition according to claim 1, wherein R is ethyl, R is 2-chloro, R hydrogen, R, R and R are each methyl.

30. A composition according to claim 1, wherein R is ethyl, R and R are each hydrogen, and R, R and R are each methyl.

31. A composition according to claim 1, wherein R is propyl, R' and R are each hydrogen, and R, R and R are each methyl.

32. A composition according to claim 1, wherein R is isopropyl, R and R are each hydrogen, R, R and R are each methyl.

33. A composition according to claim 1, wherein the compound is di'methylacetamidinej b 34. A method of combatting' helrriintic infections in humans and animals which comprises orally or parenterally administering to a human or animal in need thereof an anthelminitically effective amount of an aminophenylamidine of the formula:

carbon atoms, alkenyl of two to six carbon atoms, I alkoxyof one to six carbon atoms, or trifluoromethyl; R is alkyl of one to five carbon atoms;

R is alkyl of one to four carbon atoms, alkenyl of two to four carbon atoms, alkynyl of two to four carbon atoms, or cycloalkyl of three to six carbon atoms; and

R is hydrogen, alkyl of one to five carbon atoms or alkenyl of two to five carbon atoms.

35. A method according to claim 34, wherein R is hydrogen, alkyl of one to three carbon atoms or alkenyl of up to 3 carbon atoms, R is hydrogen, chlorine, bromine or methyl, R is hydrogen, chlorine bromine, alkyl of one to three carbon atoms, methoxy or trifluoromethyl, R is methyl or ethyl, R is alkyl of one to three carbon atoms and R is methyl or ethyl.

36. A method according to claim 34, wherein the compound is in the form of a salt, wherein the salt is selected from the group consisting of a hydrohalide, sulfate, phosphate, nitrate, acetate, naphthalenedisulphonate and pamoate.

37. A method according to claim 34, wherein R and R are each alkyl of one to four carbon atoms.

38. A method according to claim 34, wherein R is hydrogen, R is hydrogen, R is 2-chloro, R is methyl, R is methyl and R is methyl.

39. A method according to claim 34, wherein R is hydrogen, R" is hydrogen, R is 3-chloro, R is methyl, R is methyl and R is methyl.

40. A method according to claim 34, wherein R is hydrogen, R is 2-chloro, R is 6-chloro, R is methyl, R is methyl and R is methyl.

41. A method according to claim 34, wherein R is hydrogen, R is hydrogen, R is Z-methyl, R is methyl, R is methyl and R is methyl.

N-( 4-isobutylaminophenyl -N ',N A

42. A method according to claim 34, wherein R is hydrogen, R is hydrogen, R is Z-methoxy, R is methyl, R is methyl and R is methyl.

43. A method according to claim 34, wherein R is hydrogen, R is hydrogen, R is 2-trifluoromethyl, R is methyl, R is methyl and R is methyl.

44. A method according to claim 34, wherein R is hydrogen, R is hydrogen, R is Z-bromo, R is methyl, R is methyl and R is methyl.

1 45. A method according to claim 34, wherein R is hydrogen, R is hydrogen, R is 2-propyl, R is methyl, R is methyl and R is methyl.

46. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is ethyl, R and R are each methyl.

47. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is propyl, R and R are each methyl.

48. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is methyl and R is ethyl.

49. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is methyl and R is propyl.

50. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R and R are each ethyl.

51. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is hydrogen'and R is methyl.

52. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is hydrogen and R is ethyl.

53. A method according to claim 34, wherein R is hydrogen, R and R are each hydrogen, R is methyl, R is hydrogen and R is propyl.

54. A method according to claim 34, wherein the compound is N(4-isobutylideneaminophenyl)-N',N- dimethylacetamidine.

55. A method according to claim 34, wherein R is methyl, R is 2-chloro, R is hydrogen, R, R and R are methyl.

56. A method according to claim 34, wherein R is methyl, R is 2-bromo, R is hydrogen, R, R and R are methyl.

57. A method according to claim 34, wherein R is ethyl, R is 2-chloro, R is hydrogen, R, R and R are each methyl.

58. A method according to claim 34, wherein R is ethyl, R and R are each hydrogen, and R, R and R are each methyl.

59. A method according to claim 34, wherein R is propyl, R and R are each hydrogen, and R, R and R are each methyl.

60. A method according to claim 34, wherein R is isopropyl, R and R are each hydrogen, R, R and R are each methyl.

61. A method according to claim 34, wherein the compound is N( 4-isobutylaminophenyl )-N ',N dimethylacetamidine. 

1. A PHARMACEUTICAL COMPOSITION USEFUL FOR TREATING HELMINTIC INFECTIONS IN HUMANS AND ANIMALS COMPRISING AN ANTI-HELMINTICALLY EFFECTIVE AMOUNT OF A COMPOUND OF THE FROMULA
 2. A composition according to claim 1 wherein said carrier is a liquid or solid carrier and said composition is in oral administration form.
 3. A composition according to claim 1 wherein said carrier is a liquid carrier and said composition is in parenteral administration form.
 4. A composition according to claim 1 wherein said compound is N-(4-aminophenyl)-N'',N''-dimethylacetamidine or a pharmaceutically acceptable non-toxic acid addition salt thereof.
 5. A composition according to claim 1 wherein said compound is N-(4-methylaminophenyl)-N'',N''-dimethylacetamidine or a pharmaceutically acceptable non-toxic acid addition salt thereof.
 6. A composition according to claim 1 wherein said compound is N-(2-chloro-4-aminophenyl)-N'',N''-dimethylacetamidine or a pharmaceutically acceptable non-toxic acid addition salt thereof.
 7. A composition according to claim 1, wherein R1 is hydrogen, alkyl of one to three carbon atoms or alkenyl of up to three carbon atoms, R3 is hydrogen, chlorine, bromine or methyl, R4 is hydrogen, chlorine bromine, alkyl of one to three carbon atoms, methoxy or trifluoromethyl, R is methyl or ethyl, R5 is alkyl of one to three carbon atoms and R6 is methyl or ethyl.
 8. A composition according to claim 1, wherein the compound is in the form of a salt, wherein the salt is selected from the group consisting of a hydrohalide, sulfate, phosphate, nitrate, acetate, naphthalene-disulphonate and pamoate.
 9. A composition according to claim 1, wherein R and R5 are each alkyl of one to four carbon atoms.
 10. A composition according to claim 1, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-chloro, R is methyl, R5 is methyl and R6 is methyl.
 11. A composition according to claim 1, wherein R1 is hydrogen, R3 is hydrogen, R4 is 3-chloro, R is methyl, R5 is methyl and R6 is methyl.
 12. A composition according to claim 1, wherein R1 is hydrogen, R3 is 2-chloro, R4 is 6-chloro, R is methyl, R5 is methyl and R6 is methyl.
 13. A composition according to claim 1, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-methyl, R is methyl, R5 is methyl and R6 is methyl.
 14. A composition according to claim 1, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-metHoxy, R is methyl, R5 is methyl and R6 is methyl.
 15. A composition according to claim 1, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-trifluoromethyl, R is methylm R5 is methyl and R6 is methyl.
 16. A composition according to claim 1, wherein R1 hydrogen, R3 is hydrogen, R4 is 2-bromo, R is methyl, R5 is methyl and R6 is methyl.
 17. A composition according to claim 1, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-propyl, R is methyl, R5 is methyl and R6 is methyl.
 18. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is ethyl, R5 and R6 are each methyl.
 19. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is propyl, R5 and R6 are each methyl.
 20. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is methyl and R6 is ethyl.
 21. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is methyl and R6 is propyl.
 22. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 and R6 are each ethyl.
 23. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is hydrogen and R6 is methyl.
 24. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is hydrogen and R6 is ethyl.
 25. A composition according to claim 1, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is hydrogen and R6 is propyl.
 26. A composition according to claim 1, wherein the compound is N-(4-isobutylideneaminophenyl)-N'',N''-dimethylacetamidine.
 27. A composition according to claim 1, wherein R1 is methyl, R3 is 2-chloro, R4 is hydrogen, R, R5 and R6 are methyl.
 28. A composition according to claim 1, wherein R1 is methyl, R3 is 2-bromo, R4 is hydrogen, R, R5 and R6 are methyl.
 29. A composition according to claim 1, wherein R1 is ethyl, R3 is 2-chloro, R4 hydrogen, R, R5 and R6 are each methyl.
 30. A composition according to claim 1, wherein R1 is ethyl, R3 and R4 are each hydrogen, and R, R5 and R6 are each methyl.
 31. A composition according to claim 1, wherein R1 is propyl, R3 and R4 are each hydrogen, and R, R5 and R6 are each methyl.
 32. A composition according to claim 1, wherein R1 is isopropyl, R3 and R4 are each hydrogen, R, R5 and R6 are each methyl.
 33. A composition according to claim 1, wherein the compound is N-(4-isobutylaminophenyl)-N'',N''-dimethylacetamidine.
 34. A method of combatting helmintic infections in humans and animals which comprises orally or parenterally administering to a human or animal in need thereof an anthelminitically effective amount of an aminophenylamidine of the formula:
 35. A method according to claim 34, wherein R1 is hydrogen, alkyl of one to three carbon atoms or alkenyl of up to 3 carbon atoms, R3 is hydrogen, chlorine, bromine or methyl, R4 is hydrogen, chlorine bromine, alkyl of one to three carbon atoms, methoxy or trifluoromethyl, R is methyl or ethyl, R5 is alkyl of one to three carbon atoms and R6 is methyl or ethyl.
 36. A method according to claim 34, wherein the compound is in the form of a salt, wherein the salt is selected from the group consisting of a hydrohalide, sulfate, phosphate, nitrate, acetate, naphthalene-disulphonate and pamoate.
 37. A method according to claim 34, wherein R and R5 are each alkyl of one to four carbon atoms.
 38. A method according to claim 34, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-chloro, R is methyl, R5 is methyl and R6 is methyl.
 39. A method according to claim 34, wherein R1 is hydrogen, R3 is hydrogen, R4 is 3-chloro, R is methyl, R5 is methyl and R6 is methyl.
 40. A method according to claim 34, wherein R1 is hydrogen, R3 is 2-chloro, R4 is 6-chloro, R is methyl, R5 is methyl and R6 is methyl.
 41. A method according to claim 34, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-methyl, R is methyl, R5 is methyl and R6 is methyl.
 42. A method according to claim 34, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-methoxy, R is methyl, R5 is methyl and R6 is methyl.
 43. A method according to claim 34, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-trifluoromethyl, R is methyl, R5 is methyl and R6 is methyl.
 44. A method according to claim 34, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-bromo, R is methyl, R5 is methyl and R6 is methyl.
 45. A method according to claim 34, wherein R1 is hydrogen, R3 is hydrogen, R4 is 2-propyl, R is methyl, R5 is methyl and R6 is methyl.
 46. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is ethyl, R5 and R6 are each methyl.
 47. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is propyl, R5 and R6 are each methyl.
 48. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is methyl and R6 is ethyl.
 49. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is methyl and R6 is propyl.
 50. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 and R6 are each ethyl.
 51. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is hydrogen and R6 is methyl.
 52. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is hydrogen and R6 is ethyl.
 53. A method according to claim 34, wherein R1 is hydrogen, R3 and R4 are each hydrogen, R is methyl, R5 is hydrogen and R6 is propyl.
 54. A method according to claim 34, wherein the compound is N-(4-isobutylideneaminophenyl)-N'',N''-dimethylacetamidine.
 55. A method according to claim 34, wherein R1 is methyl, R3 is 2-chloro, R4 is hydrogen, R, R5 and R6 are methyl.
 56. A method according to claim 34, wherein R1 is methyl, R3 is 2-bromo, R4 is hydrogen, R, R5 and R6 are methyl.
 57. A method according to claim 34, wherein R1 is ethyl, R3 is 2-chloro, R4 is hydrogen, R, R5 and R6 are each methyl.
 58. A method according to claim 34, wherein R1 is ethyl, R3 and R4 are each hydrogen, and R, R5 and R6 are each methyl.
 59. A method according to claim 34, wherein R1 is propyl, R3 and R4 are each hydrogen, and R, R5 and R6 are each methyl.
 60. A method according to claim 34, wherein R1 is isopropyl, R3 and R4 are each hydrogen, R, R5 and R6 are each methyl.
 61. A method according to claim 34, wherein the compound is N-(4-isobutylaminophenyl)-N'',N''-dimethylacetamidine. 